The present invention relates to locks and more particularly but not exclusively to door locks.
Known deadlocks enable a user by operation of a key to xe2x80x9cdeadlockxe2x80x9d the lock from the inside. This creates a problem in that should a person inside be unable to locate a key they will not be able to exit. This is of particular danger should a fire occur.
Described in Australian Patents 702534 and 692915 are locks having the above problem.
Frequently locks, such as the lock of Patent 692915 are configured such that a user entering from the outside by use of a key disables the deadlock mechanism so that a person cannot accidentally lock themselves inside by merely closing the door.
It is the object of the present invention to overcome or substantially ameliorate the above disadvantage.
The lock includes:
a lock tongue member movable between an extended striker engaging position and a retracted position;
an actuator on a first side of said lock and which is manipulated by a user to move the tongue member from the extended position to the retracted position;
a lock mechanism operatively associated with said actuator and being arrangable in a first configuration and a second configuration, said mechanism wherein said first configuration permitting operation of said actuator to move the tongue member from the extended position to the retracted position, while wherein said second configuration rendering said actuator ineffective in respect of moving said tongue member from said extended position to said retracted position;
a first key operable lock cylinder, said first cylinder being on said first lock side and operatively associated with said lock mechanism;
a second key operable lock cylinder, said second cylinder being on a second side of said lock and operatively associated with said lock mechanism; and wherein
said lock mechanism is responsive to operation of said first cylinder by a user to be arranged in said first configuration but not said second configuration, while being responsive to operation of said second cylinder by a user to be arranged by choice of said user in said first configuration or said second configuration.
Preferably the tongue member includes a tongue portion and a base portion, with the base portion mounting the tongue member for angular movement between the extended and the retracted positions of the tongue member, with the tongue portion being of a hook configuration.
Preferably the lock further includes a projection movable, relative to the tongue member, between a first position retaining the tongue member in the extended position and providing said second configuration, and a second position permitting movement of the tongue member and providing said first configuration, and a cam member mounted for angular movement to cause movement of the projection between the first and second positions thereof, with said cam member and projection being part of said lock mechanism and moved by operation of the first and second cylinders.
Preferably each cylinder includes a barrel, with the barrels, tongue member and cam member being angularly movable about a common axis.
Preferably the lock further includes a pawl mounted on said cam member, the pawl being adapted to prevent operation of said first cylinder to arrange said lock mechanism in said second configuration.
Preferably said pawl is movable parallel to said axis between a first position at which said cam member is movable by said first cylinder, and a second position at which said first cylinder is incapable of moving said cam member.
Preferably said fist cylinder when moved angularly in a first direction moves the pawl to the pawl second position so that angular movement of the first cylinder in said first direction does not move said cam member, while angular movement of said first cylinder in the opposite angular to said first direction causes engagement of the first cylinder with the pawl to thereby move the cam member and thus movement of said projection from the projection first position to the projection second position.
Preferably the lock further includes a spring urging said pawl in the pawl first position.
Preferably the lock further includes a spring urging said projection to the first position thereof.
In a further preferred form the lock further includes:
a recess in said tongue member;
a projection movable with respect to said tongue member between a first position at which the projection is located in the recess preventing movement of the tongue member and thus providing said second configuration, and a second position spaced from the recess so as to permit movement of the tongue member and thus providing said second configuration;
a cam member operatively associated with the projection to cause movement of the projection between the first and the second positions thereof; and wherein
the first cylinder is operatively associated with the cam member so that the cam member can only be driven in one rotational direction by the first cylinder, with angular movement of the cam member in said one direction providing for movement of the cam member to cause movement of said projection to release the tongue member, while said second cylinder is operatively associated with the cam member so as to be operable to drive the cam member in both rotational directions to thereby provide for movement of said projection to either of the positions thereof.
Preferably the lock further includes a pawl mounted on said cam member, the pawl being adapted to prevent operation of said first cylinder to arrange said lock mechanism in said second configuration.
Preferably said cam member is angularly moved about an axis, and said pawl is movable parallel to said axis between a first position in which the cam member is movable by said first cylinder, and a second position at which said cam member is incapable of moving said cam member.
Preferably rotational operation of the said first lock cylinder in one angular direction only, changes the operative configuration of the lock mechanism, while rotational operation of said second lock cylinder in either angular direction changes the operative configuration of said lock mechanism.
Preferably the lock further includes a projection movable, relative to the tongue member, between a first position retaining the tongue member in the extended position and providing said second configuration, and a second position permitting movement of the tongue member and providing said first configuration, and a cam member mounted for angular movement about an axis and to cause movement of the projection between the first and second positions thereof, with said cam member and projection being part of said lock mechanism and moved by operation of the first and second cylinders.
Preferably the lock further includes a pawl mounted on said cam member, the pawl being adapted to prevent operation of said first cylinder to arrange said lock mechanism in said second configuration.
Preferably said pawl is movable parallel to said axis between a first position at which said cam member is movable by said first cylinder, and a second position at which said first cylinder is incapable of moving said cam member.
Preferably said tongue member pivots about said axis to move between the tongue extended and retracted positions.
Preferably the lock cylinders are co-axial with respect to said axis.
Preferably said actuator is rendered ineffective to move the tongue to the retracted position by said tongue member being retained in the extended position.
Preferably said actuator is a lever that pivots about said axis to move the tongue member.